I need to exclude arbitrary chunks of my documents from Markdown
parsing, because my documents are littered with <?php blah blah ?>,
and a few other oddities. These blocks get gifted with unwanted
markup by Markdown:

<?php blah blah ?> becomes <p><?php blah blah ?></p>

If I can't make it stop that, it's a dealbreaker for me in an
otherwise fascinating and incredibly useful tool. And my gut tells
me that there has *got* to be a way, even though I've scoured the
syntax docs and can't find it. (I did notice a mechanism for doing
this via WordPress (<MTMarkdownOptions output='raw'>), but that's
WordPress. I'm handcrafting documents in BBEdit.)